Janis Joplin performing in San Jose, California, in 1968.

"Janis wasn't the prettiest but she was not afraid of the camera," says Marshall. "She was the most upfront girl. You could just call her at home and be like, 'We have to take some pictures,' and she?d say, 'OK! Come over!' She trusted me and knew I had her best interests at heart. I only wanted to make her look good."